Can Head Lice Spread Disease or Infections?

by Jennie Lasater, founding owner of Lice Ladies

One of the questions that I get asked on a daily basis is: Can head lice spread blood disease or infections? As of right now, head lice are not known to spread disease. However, sometimes the itching from the bites can lead to excessive scratching that can sometimes increase the chance of a secondary skin infection.

Let’s take a deeper look at this.

The head louse, or Pediculus humanus capitis, is a parasitic insect that infests the hair on a human head. Head lice feed from the blood on the human scalp. Adult lice are six-legged, wingless insects 2-4 mm long. They are brown when they have fed (remember they are feeding on our blood). Their heads have two tiny eyes and two small antennae. Six pairs of hooks surround the mouth, by which they attach themselves to the skin of the scalp for feeding. The mouth contains two retractable, needle-like tubes that pierce the scalp. Salivary juices are injected into the scalp with anticoagulant properties to prevent blood from clotting. The lice feed by sucking blood through these same tubes.

Lice completely depend on the blood extracted from humans for existence, and thus will starve to death after approximately 48 hours without human blood. We know that lice can live on a human host for 30 days, during this time, the females generally lay from 6-8 eggs per day.

During this whole life cycle, larvae and adult lice deposit their feces in the scalp, which eventually causes itching as the person develops an allergic reaction to the lice stool or the bites (allergies to the louse salivary juices or simply from scratching the bites etc…). The general symptom of head lice is “itching,” but a person may have lice for months before the itching begins.

Most people don’t get any sort of skin infection from scratching lice bites…however excessively scratching any type of bite or wound can cause infections.

Let me repeat so people don’t panic without cause….Most people don’t get skin infections from scratching lice bites…but if people are excessively scratching these bites on their scalps, they can become infected just like any other bite or wound can become infected.

Here are the some general infections that can be caused from excessively scratching and/or infecting wounds or bites:

The staph infection

Staph infections are caused by staphylococcus bacteria. This is a type of germ is commonly found on the skin or in the nose of most people. Most of the time, these bacteria cause no problems or result in relatively minor skin infections. But staph infections can turn deadly if the bacteria invade deeper into your body, entering your bloodstream, joints, bones, lungs or heart.

Skin infections caused by staph bacteria include:

-Boils. The most common type of staph infection is the boil, a pocket of pus that develops in a hair follicle or oil gland. The skin over the infected area can become red and swollen. If a boil breaks open, it may drain pus or blood.

-Impetigo. This contagious rash is most common in young children and infants. The types of impetigo caused by staph bacteria usually are large blisters that may leak fluid and develop a crust.

MRSA

Methicillin-resistant Staphylococcus aureus are Staphylococcus bacteria that have become resistant to certain antibiotics, like penicillin, amoxicillin or augmentin. This has made it difficult to treat. Usually, MRSA is a skin infection although it can turn into much more serious types of infections if not treated.

Cellulitis

Cellulitis is an infection at the subcutaneous layer. This kind of infection is caused by bacteria, which can get into the body through broken skin of any kind. Oozing sores and ulcers can develop.

Cellulitis is very serious and someone who has it needs to contact their doctor immediately. It can cause fever, chills, and swollen glands. Medical attention needs to be sought before bacteria gets into the bloodstream or bones. Usually IV antibiotics are administered.

Yeast infections of the skin/scalp caused by excessive scratching

It’s always very important to follow your doctor’s treatment instructions, with or without antibiotics for any of these types of infections. As with any illness or infection, seek medical attention.

More skin/scalp conditions that may already be present regardless if someone has a head lice infestation:

Ringworm of the Scalp (Tinea Capitis) – Ringworm of the scalp is not really a worm, but a fungal infection also called Tinea capitis. It causes patches of itchy and scaly skin on the scalp. This is becoming much more common among school children.

Lichen planus is a fairly common skin rash that is thought to be triggered by the immune system. Symptoms include purplish lesions that itch and spread. It can cause irritation on the scalp and hair loss.

Nutritional Deficiencies and Hyperthyroidism can also cause hair loss.

Yeast infections of the skin/scalp can also already be present simply from excessive scratching from nervous habits, scratching with un-washed hands and fingernails, etc..

Cradle cap is a crusting and scaling rash found on the scalps of many babies. It is commonly referred to in teens as seborrhea. Usually this disappears in most babies within their first few years. However, it can be present on children and teens during puberty and can also be a life-long condition. Physicians may recommend prescription-strength antifungal and corticosteroid shampoos or medications for seborrhea.